


The Mystery of Professor Yamaguchi's Husband

by spadebrigade



Category: Haikyuu!!
Genre: Aged-Up Character(s), Alternate Universe - College/University, Alternate Universe - Professors, Domestic Fluff, Established Relationship, Everyone Is Gay, F/F, Fluff, Humor, M/M, One Shot, POV Yachi Hitoka, Slice of Life, Tsukkiyama Week, especially yachi, like it's barely there, middle aged tsukishima and yamaguchi, very minor kiyoyachi
Language: English
Status: Completed
Published: 2020-09-01
Updated: 2020-09-01
Packaged: 2021-03-06 19:35:53
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,348
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26234275
Author URL: https://archiveofourown.org/users/spadebrigade/pseuds/spadebrigade
Summary: Oversharing astronomy professor Yamaguchi loves going on about his beloved husband Kei...And students of paleontology professor Tsukishima wonder who would put up with being married to such a tight-lipped man. But a small group of unfortunate students in both classes learn the truth: their two professors, as opposite as night and day, are married toeach other.
Relationships: Tsukishima Kei/Yamaguchi Tadashi
Comments: 217
Kudos: 2558
Collections: TsukkiYama Week 2020, stories that touched me





	The Mystery of Professor Yamaguchi's Husband

**Author's Note:**

> **this fic has now been[translated into russian!!](https://ficbook.net/readfic/9893012)**
> 
> the idea for this fic was based on [this tumblr meme.](https://64.media.tumblr.com/ee27e50140b8bec55662aa0831e16d67/tumblr_inline_qfui5gmKjY1x417o9_500.png) i had a great time writing this and vibing with luna ([@lvnesart](https://www.instagram.com/lvnesart/)). scroll to the bottom to see the amazing art they made for this fic!

It began with an innocent conversation. Yachi couldn’t help it—Professor Yamaguchi was such a _cool_ astronomy professor. He was in his thirties but still rocked earrings and a ponytail, and wore the coolest galaxy accessories she’d ever seen. On that particular Monday, he’d shown up to class with a deep blue tie, speckled with shades of turquoise and purple and an infinite amount of stars. So _of course_ she had to compliment it. But it was his answer that threw the whole class off.

“Thank you! My husband got it for me.” 

Yachi had taken a sip of her water and nearly choked at the ‘h’ word, thankfully regaining her composure quickly enough to hear another student ask, “Your husband, sir?”

“Yes,” He answered with an absentminded smile, turning on the projector. “We have this silly tradition. Because we’ve been together so long, gifts are kind of pointless. So we buy each other things related to our fields. I have so many ties, shirts, shoes—all with stars on them.”

It was one thing to have a cool professor—but an _openly gay_ professor? It made her day. Actually, no—it made her _semester._

Another student chimed, “So he’s a professor too?”

“He is.” Yamaguchi waved his hand with a laugh, dismissing further questions. “Now, now. Let’s begin our lesson.”

But that didn’t stop Yamaguchi (he let them drop the “Professor”) from sharing things about his husband unprompted. Over the course of their class, throughout the weeks, they came to learn a lot about “the other Mr. Yamaguchi”: his name was Kei, he had a major sweet tooth, he hated loud noises, and his glasses always fogged up with steam when he drank coffee. The students all had this image of Kei Yamaguchi as a shy, chubby man with kind eyes. Every mention of him made Yachi smile to herself in her seat. What she’d give to have a cute girlfriend like that...someone whose eyes oozed with fondness when they talked about her. 

But while Professor Yamaguchi’s class gave her warm and fuzzy feelings, not every professor was quite as...pleasant.

Dr. Tsukishima was _very_ different from Professor Yamaguchi. He was so serious-looking: short blond hair, sharp eyes behind browline glasses, and he always wore earth-toned sweaters. It was only her first year of college, and Yachi never thought she’d have two teachers that were such opposites. Where Professor Yamaguchi was caring and smiley, Dr. Tsukishima was cold and dry.

“Some of your professors may ask you to call them by their first names,” He said on the first day of their intro-level paleontology class. “That will not be the case here. You may refer to me as ‘Dr. Tsukishima’ or, if you want to be chummy, ‘Professor Tsukishima’. And before you ask, no, we will not be watching Jurassic Park in this class.”

Yachi quickly discovered that his first name wasn’t even listed on the syllabus. What a weirdly strict professor! She recounted all of the details to her study buddy Oikawa later, who was also in Yamaguchi’s class. 

“Ehh,” he sighed, leaning back in the uncomfortable library chair. “Do you think he’s like Rumplestiltskin? Like if you figure out his name, you get a wish?”

That got her giggling, until a librarian came over to shush her, which got _Oikawa_ giggling, and then made her giggle even more. They really had to stop studying in the library. 

♤

Yachi was a good student. Heck, she’d even say that she was a _great_ student. For as long as she could remember, she was the favorite of all her teachers. A few classes with her, and they’d be practically swooning over her color-coded notes and her unbreakable work ethic. So _why_ couldn’t she get along with Dr. Tsukishima?

She always got to class early and always sat in the front row, her enthusiasm for learning buzzing inside of her. 

“Before we begin class, does anyone have any questions?”

“P-professor,” she began, already hating herself for stuttering, “how was your weekend?”

He returned her bright-eyed look with a blank one. “I should have been clearer: does anyone have any questions _related to the material?”_ When someone snickered in the back row, he rolled his eyes. “In a few weeks, all of you will be complaining about how stressed you are about the upcoming exam. I don’t want to hear about how I go too fast or don’t explain things when you’re not using your time appropriately.”

The semester carried on. With midterms approaching, no one had the time or even had the thought to try to figure out who Professor Yamaguchi’s husband was—except for Yachi’s study group.

“Do you think his husband works here too?” Oikawa asked one day, when they were supposed to be going over equations. They had taken refuge in an empty classroom, where they could talk freely without being the victims of librarians’ glares.

Akaashi, another member of their study group, clicked his tongue. “Not necessarily. Has he ever told the story of how they met?”

Yachi sighed, laying her head against the desk. “He’ll go on and on about Kei, but any time we ask a question, he’ll suddenly remember he’s teaching and change the subject.” 

She loved listening to Yamaguchi’s lectures, but she also wanted to _know_ about their story. Maybe if she figured out who Professor Yamaguchi’s husband was, and how they met, she’d be able to figure out how to get a girlfriend of her own. Or that was what she told herself, anyway, because she was so unlucky in love that she figured _any_ information would be of use to her. The last time she tried asking out a girl, she’d gotten a too-friendly “you’re so cute” and a pat on the head. The most embarrassing part was that she’d been _older_ than the girl she was talking to. Yachi didn’t know how she’d survived that encounter, but she was going to make sure that it never happened again.

She noticed something interesting during the next class when Dr. Tsukishima handed back their midterms. Before she could stop herself, the words came tumbling out: “You’re married, professor?” His wedding band glinted in the light as he continued passing them out.

“Yes. What of it?”

The classroom erupted. Questions filled the air: what was his spouse like, how long were they married, who could be willing to put up with such a terrible personality?

“What was that last part?” He asked, turning his cold stare upon his students, who laughed. “Maybe I should take back the curve on this exam—”

“No, no! You’re a catch!”

He shook his head. “Make sure you review the powerpoints next time.”

Yachi didn’t find any more clues until she went to Dr. Tsukishima’s office hours, because she definitely deserved at least a 98% instead of the 94% he gave her. She walked through the halls of the Paleontology building, passing by wooden doors marked with custom name plates, flyers for school events, dinosaur posters, and political cartoons. Finally, she stopped at Dr. Tsukishima’s door, which was only marked by the university-provided name plate. Her knuckles hesitantly met the wood, before hearing, “Come in.”

She entered to find Dr. Tsukishima at his desk, poring over a stack of papers and a half-eaten brownie. “Miss Yachi. Is this about your midterm?” Seeing her nod vigorously, he gave an amused smile, before gesturing to a chair. “Have a seat.”

She did, half expecting spikes to pop out of the chair and impale her. But when her butt met the cushion, she found that it was surprisingly comfortable. Her eyes swept the room: the walls were covered in diagrams of dinosaurs and their bones, photos from digs that Dr. Tsukishima had been on, and the shelves held neat rows of books, some of which had his name down the spine. She would have described it as a “nerd cave” if there wasn’t so much light streaming through the windows.

“What did you have an issue with?” His question made her jump. 

“Ah,” She pulled the exam out of her folder. “You see, it was…” She went on about the question, watching as he took the paper from her to think it over. He took a sip of coffee, blowing on it in a way that fogged up his glasses for a moment. 

Somehow, the conversation ended up evolving into common fossil misconceptions, resulting in the professor huffing and saying “Don’t even get me started on Dilophosauri,” only to do just that. And then she sat there, wide-eyed, as their conversation turned into a monologue on the difference between venom and poison. 

“So basically, he nerded out,” Oikawa said later at their usual classroom, barely holding back laughter. 

Yachi shook her head. “It was really cute, though! His eyes got all sparkly.”

“Maybe he’s only mean as a persona?” Akaashi offered, twirling his pencil in his fingers. “So he’ll be taken seriously.”

“I don’t know…” She recalled the time she was in an elevator with him, and when he saw someone else approaching, he pressed the ‘close door’ button.

Oikawa scoffed. “So? I do that, too.”

Akaashi returned his attention to his textbook. “That’s because you’re also a jerk.”

“Hey!”

Yachi didn’t think that Dr. Tsukishima was a jerk, though. He was definitely serious: he never let them get off track for too long in class, gave them lots of pop quizzes, and snapped whenever someone’s phone went off. But he spoke with such passion, and always made plenty of teasing jokes. She could see, objectively, why someone would want to marry him. 

During class one day, she accidentally let that last fact slip out of her mouth. And to her horror, the professor heard.

“How kind of you, Miss Yachi.” He rolled his eyes, making the class burst into giggles. “I’ll be sure to tell my husband.”

“HUSBAND?!” The class erupted. He immediately realized his mistake, pushing up his glasses in irritation at the endless stream of questions.

“Since you’re all so full of energy, I’ll be uploading extra articles for you to read tonight. Come to my office if you have any _course-related_ questions.”

Yachi was too stunned to point out that he had already uploaded those extra articles yesterday, but she presented the information to her study group later.

 _“He’s_ gay too?!” Oikawa gasped. “Is there something in the water here?”

Akaashi clicked his tongue. “You were queer before you drank the water here.”

“So were you! And Yachi too.”

“Guys!” She clapped her hands together. “That’s besides the point. If Dr. Tsukishima and Professor Yamaguchi are both…uh…” She struggled to find the right words—“gay nerds,”—that sounded right, “...then maybe they know each other!”

Akaashi shrugged. “Maybe, but they’re in different departments.”

“Ah, you’re probably right.” And the Paleontology department was on the opposite side of campus from the Astronomy department, so it wasn’t like they would cross paths. “It wouldn’t be likely.”

All the clues came together in a way that Yachi would never have expected. It was after their second paleontology exam, on the day Dr. Tsukishima was supposed to hand back the tests. And he was ten minutes late.

The classroom stirred. “He’s never been late before.”

“Five more minutes and we get to leave, right?” 

Yachi drummed her fingers nervously against the desk. Her brain was beginning to come up with all kinds of horrible scenarios, each more radical than the next, beginning with “maybe he missed his train” and ending with “maybe he was kidnapped by yakuza.” But at minute fourteen, the professor walked in, hair disheveled and out of breath. 

“I apologize, everyone.” Dr. Tsukishima hurried to the podium, setting down his bag. “My neighbors held a party last night and were so disgustingly loud that I couldn’t sleep, and I missed my alarm this morning.” His words were punctuated by the visible bags under his eyes. 

Yachi swallowed her concern.

They got straight into the lesson. A few minutes in, his phone buzzed from the podium, and he silenced it. But he must have been getting more notifications, because his eyes kept wandering over as he gave the lecture.

Someone in the back raised their hand. “Is everything okay, professor? Your phone…”

He sighed. “Again, I’m very sorry to use your time like this. It may be an emergency. Take a five minute break, everyone.”

Murmuring, some students left their seats. Yachi, however, remained glued to the front row. She wasn’t eavesdropping…The professor just happened to be on the phone right there.

Dr. Tsukishima held his phone to his ear, speaking quietly. “What is it, Tadashi? I’m teaching.”

She tried not to lean too far forward, straining her ears to listen.

His eyes widened. “I did? I must have done it last night without thinking...right. Are you on campus? ...Okay. Love you too. Bye.”

She nearly jumped out of her seat. So Dr. Tsukishima’s husband was named Tadashi! If she could just find out more, then maybe she would know who Professor Yamaguchi’s husband was, too. Yachi sat there plotting until their impromptu break was over, and the professor apologized again.

“It seems that I accidentally switched folders with my husband. He’s nearby, so he’ll bring them over.”

Ignoring the typical barrage of questions, he continued on with his lecture. When class was nearly over, there came a knock at the door.

“Sorry to interrupt.” Came a familiar voice. Yachi turned to find Yamaguchi standing at the door, folder in hands. Her mouth fell open.

Dr. Tsukishima frowned. “You could have texted me.”

“I did,” Yamaguchi laughed. “You must have been too into your lecture. I need my students’ exams too, so hand them over.”

As Dr. Tsukishima turned to do just that, Yamaguchi directed his attention to the class. “Sorry about that, everyone! Kei gets grumpy when he doesn’t sleep enough. He spends the whole day wrinkling his nose like he smelled something bad."

 _“Tadashi.”_ Dr. Tsukishima said, handing him the folder. _“Thank you._ That’s all I need.”

“Oops! Sorry, Kei.” He said, not sounding sorry at all. Then his eyes found Yachi’s, and he sent her a warm smile, killing her instantly. “Thanks for your patience, everyone.” He walked out the door, like he hadn’t just unearthed the greatest news in history.

Dr. Tsukishima paid no attention to the stunned looks on everyone’s faces (Yachi had almost forgotten to close her mouth), and continued on with the lecture. Five minutes later, someone raised their hand.

“Yes, Mr. Haiba?”

“Is your husband a professor?”

The professor exhaled slowly, pinching the bridge of his nose. “You all can leave early today.”

♤

Yachi felt like she could burst from this revelation. Professor Yamaguchi’s husband was _Dr. Tsukishima._ The cold, sarcastic dinosaur professor was the one that loved sweets and bought starry ties and earrings for his spouse, and who even after all this time could make his husband swoon and sigh. She had finally solved the mystery, but her heart ached with jealousy. It wasn’t that she didn’t want them to be happy together—of course she did—but when was she going to get a hot nerdy wife? Was she really going to have to wait until she was thirty?

She didn’t get too much time to think about it in between her back-to-back classes, though, and was wondering how to word all of the information in a text to her study group as she walked down a hallway. She was so distracted by her phone that she didn’t notice until it was too late.

“You know, you didn’t have to make a whole display in front of my students.” It was Dr. Tsukishima’s voice, just around the corner.

A laugh—Professor Yamaguchi’s. “I couldn’t help it. I know you’re very secretive with them.”

Yachi shrunk back, feeling like she was intruding on something private even though she’d just been walking through this very public hallway. 

“I have a reputation to uphold, Tadashi. What will I do when my students find out how much I love my adorable husband?”

“I don’t think it’s that big of a deal, silly.” Then, a wet kissing sound that made her cheeks burn. “I’ll see you at home.”

The footsteps became louder, and Yachi froze. Should she run away?! 

Her time ran out—Professor Yamaguchi blinked at her. 

“Oh, hello Yachi.” He smiled, as though she was not guilty of a horrible crime. “I didn’t know you were Kei’s student. I was surprised to see you today.”

Blushing furiously, phone still in her hands, she nodded her head like a happy dog’s wagging tail.

“I hope he isn’t too mean to you.” He looked around, before stage whispering, “He’s actually a big softie.”

“Y-yes, sir! I mean, no sir!” Yachi squeaked. “H-he’s very nice.”

“Good,” He smiled, satisfied. “I’ll see you next class.”

“Yes, sir!”

When he left, she finally let out a breath. Oikawa and Akaashi weren’t going to believe this.

♤

Oikawa shook his head after hearing all of the details. “That’s _wild.”_

Akaashi nodded in agreement. Even _he_ had abandoned his notes, leaning forward on his elbows. “Do you think they met at work?”

“Oh ho~ Why, Akaashi?” Oikawa said, nudging him. “Are you going to look for your future man when you get a job?”

Yachi was about to interject when Akaashi defended himself by rolling his eyes. 

“I don’t know if I can look either of them in the eye again.” Yachi placed her head on the desk. “I totally snooped.”

Akaashi informed her that she, in fact, had not violated anyone’s privacy by existing in their proximity. But she still felt bad about it.

She spent the next two days trying to figure out how to properly apologize for being nosy. She’d concocted a whole plan and speech about just how regretful she felt, but then she ran into Yamaguchi before class and all the words tripped out of her mouth, from beginning to end.

He threw back his head in laughter. “You’re apologizing for finding out who my husband is?”

“Y-yes…”

“Yachi,” he said, words shaking from laughter, “That’s not classified information.”

“Then why don’t you have the same last name?”

He wiped a tear from his eye. “We both published research before we got married, so it was easier to keep our maiden names.”

“But then how come Dr. Tsukishima never told us anything about you?”

“He thinks that his students will walk all over him if they find out too much about his personal life.” Yamaguchi said, moving his hand in a ‘what-can-you-do?’ gesture. “He’s the kind of person who feels like his privacy is invaded if you ask him what kind of sandwich he’s eating.”

Yachi wilted. So it hadn’t been much of a mystery after all. 

An amused smile overtook his face. “You seem very interested in this.” 

“I—well…” She held her books closer to her chest. “I just see how happy you are together and—and I hope that I can find someone who’s as perfect for me as you and Dr. Tsukishima are for each other.”

Yamaguchi smiled. “Don’t worry. One day, you will.”

As he said that, something moved in the corner of her eye. She turned her head to see the most beautiful girl walking past. Silky black hair cascaded down her shoulders—was that a mole on her cheek? 

“Right,” Yachi said distractedly, staring at the girl, who had now crossed to the other end of the hallway. “I’ll meet you in the classroom, professor.”

‘One day’ was too far away, she decided as she took off down the hallway.

* * *

**Artwork by[@lvnesart](https://www.instagram.com/lvnesart/) <3**

poster:

scenes from the fic: 

(Left: Dr. Tsukishima and Yachi in the elevator. As Koganegawa approaches, Tsukki presses the "close door" button and Yachi sweats nervously.

Top right: Yachi is sitting across from Dr. Tsukishima in his office as he goes on a heated rant about dinosaurs.

Bottom right: The attractive Professor Yamaguchi giving us a wink.)

like this art [on instagram](https://www.instagram.com/p/CElK6fVF1_m/) or reblog it [on tumblr](https://lvnesart.tumblr.com/post/628073745795465216/tskym-week-day-7-free-day-collab-with)

**Author's Note:**

> thank you so much for reading! and special thanks to [chan](https://bokuakasalways.tumblr.com/) for being my support and lovely beta
> 
>  **EDIT:** for a funny one shot where yachi continues her adventures (inspired by this fic), click [HERE](https://archiveofourown.org/works/26517115)
> 
> find luna on: [instagram](https://www.instagram.com/lvnesart/?hl=en) | [ tumblr](https://lvnesart.tumblr.com/) | [ao3](https://archiveofourown.org/users/l_moongod)  
> find me on: [instagram](https://www.instagram.com/spade.yy/) | [tumblr](https://spadebrigade.tumblr.com/)

**Works inspired by this one:**

  * [The Case of the Two Fighting Professors](https://archiveofourown.org/works/26517115) by [orphan_account](https://archiveofourown.org/users/orphan_account/pseuds/orphan_account)




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